Mineral lubricating oils containing phosphite-molybdenum pentachloride reaction products



United States Patent 3,201,348 MINERAL LUBRICATING OILS CONTAININGPHOSPHITE MOLYBDENUM PENTACHLO- RIDE REACTION PRODUCTS Edwin L. DeYoung, Milwaukee, Wis., assignor to Standard Gil Company, Chicago, 111.,a corporation of Indiana No Drawing. Filed Dec. 19, 1960, Ser. No.76,471

7 Claims. (Cl. 252-325) a The herein disclosed reaction products of themolybdenum pentachloride and dialkyl phosphites are claimed in mycopending divisional application Serial No. 138,217, filed September 7,1961, now US. Patent 3,093,669.

This invention relates to novel organo-molybdenum derivatives and moreparticularly to oil-soluble reaction products of molybdenumpentachloride and hydrocarbyl substituted phosphites, which productsimpart resistance to oxidative deterioration when incorporated inlubricating oil compositions.

Within recent years it has become common practice to impart improvedproperties to lubricants through the use, of various types of additivesor addition agents. Lubricating oils employed in internal combustionengines such as automotive and diesel engines require the use of one ormore addition agents to improve their serviceability under certainadverse operating conditions. Among the more important additivesemployed are the type which function to prevent the formation andaccumulation of sludge and varnish-like coatings on pistons and cylinderwalls of the engine. Such additives which have the property ofmaintaining clean engines are referred to as detergent-type lubricantadditives. The more effective addition agents which have been developedfor compounding with lubricants are many sulfur-containing organiccompounds such as, by way of example, sulfurized terpenes, sulfurizedhydrocarbon oils, vegetable oils or animal oils, organic polysulfides,particularly polyalkyl polysulfides, metal salts of organo-substitutedthioacids of phosphorus, metal salts of the reaction product of aphosphorus sulfide and a hydrocarbon such as, for example, polybutenesand other polyolefins, and combinations of the foregoing.

Corrosion inhibitors also play an important part in the formulation ofefficient lubricants. Such corrosion inhibitors should efiectivelyinhibit the corrosion of metal alloys of the type used in enginebearings and other engine parts. Recent increased use of silver andsimilar metals in the construction of improved internal combustionengines has created new problems in the use of sulfur-containingadditives in lubricants for such engines; the primary problem createdbeing the corrosion of such silver parts of the engine by thesulfur-containing additives. While such corrosion can be eliminated byavoiding the use of sulfur-containing additives in lubricants for suchengines, this solution of the problem is accompanied by the loss of thehighly desired beneficial effects of the additives of this type.

An object of the present invention is to provide novel oil-solubleorgano-molybdenum compounds and a method of preparing the same. Anotherobject is to provide novel oil-soluble organo-molybdenum compoundshaving particular utility as lubricant additives. A particular object isto provide novel oil-soluble reaction products of molybdenumpentachloride and hydrocarbyl substituted phosphites which haveanti-oxidative properties in addition to having substantial metalcorrosion inhibiting properties when added to mineral lubricating oils.A further object is to provide a composition which will inhibit thecorrosion of silver and similar metals by sulfur and/ or organic'sulfur-containing compounds. Still another object is to provide amethod of inhibiting the corrosion of engine parts rosive to metals withwhich such lubricants are in contact.

Thus, in accordance with the present invention, the oilsoluble reactionproducts of molybdenum pentachloride are prepared by reacting molybdenumpentachloride with a hydrocarbyl substituted phosphite having thegeneral formula (RO) -POH wherein R is a hydrocarbyl radical containingat least four carbon atoms. actants being employed in the molar ratio ofabout one mole of molybdenum pentachloride to about three molesof thehydrocarbyl substituted phosphite, preferably with a slight excess ofthe phosphite reactant. The reaction is carried out at atmosphericpressure and at temperatures of from 20 C. to about 140 C. Dependingupon-the temperatures employed, the reaction time may vary from abouttwo hours to about 16 hours.

The new products are viscous liquids of varying oil solubility dependingupon the amount and nature of hydrocarbon substitution in the structureand nature'of the base oil. They have particular value as anti-oxidantsfor lubricating oil lubricants, as bearing corrosion inhibi' tors and,because they are non-corrosive to silver in lubricant compositions, havea wide range of applicability. In general, it is desirable that thehydrocarbyl substituted phosphite reactant contain at least four carbonatoms, preferably 8 to 18 carbon atoms, in the hydrocarbyl substituentin order to provide adequate oil solubility in the final reactionproduct. The products then can be handled in the form of mineral oilconcentrates which facilitate handling in the formulation of commerciallubricating oils and greases. The level of use in the finishedlubricant, however, is usually quite small. For use as an oxidationinhibitor in a hydrocarbon oil susceptible to oxidative deteriorationthe concentration of the additive should be at least 0.2% by weight.Amounts above 0.5% give satisfactory results, but since such results maybe obtained with lesser amounts, it is usually not economical to employmore than 0.5

In commercial formulations, the hydrocarbyl substitutedphosphite-molybdenum pentachloride reaction products will ordinarily beused, as is customary in conjunction with other compatible lubricatingoil additives,

for example, pour depressants, viscosity index improvers, anti-rustagents, anti-foam agents and the like. The base may comprise anyhydrocarbon oil subject to oxidative deterioration. For mostapplications, the oil will comprise a mineral form fraction of the usualviscous lubricating oil range.

More specifically the novel oil-soluble organo-molybdenum products ofthe present invention are the reaction.

ample wherein di-(Z-ethylhexyl) phosphite is shown by way of example asrepresentative of the class of di-hydro- The re-- carbyl substitutedphosphites which are suitable for purposes of the present invention. Inthe example, the additive was evaluated by means of the ModifiedStirring Sand Corrosion Test (MSSCT) and the modified EMD silver bearingcorrosion test.

The MSSCT test was run as follows: A copper-lead test specimen islightly abraided with steel wool, washed with naphtha, dried and weighedto the nearest milligram. The cleaned copper-lead test specimen issuspended in a glass beaker, cleaned with a hot tri-sodium phosphatesolution, rinsed with water, acetone and dried, and 300 grams of the oilto be tested, and 50 grams of a 30-35 mesh sand charged to the beaker.The beaker is then placed in a bath or heating block and heated to atemperature of 330 F. (:2 F.) while the contents are stirred by means ofa stirrer rotating at 1300 r.p.m. The contents of the beaker aremaintained at this-temperature for forty-eight hours, after which thecopper-lead test specimen is removed, rinsed with naphtha, dried andweighed. The test specimen is then replaced in the beaker and the testcontinued for another twenty-four hours (seventy-two hours total). Atthe conclusion of this time, the test specimen is removed from thebeaker, rinsed with naphtha, dried and weighed.

In the modified EMD test a silver strip 2 cm. x 5.5 cm. with a smallhole at one end for suspension is lightly abraded with No. 0 steel wool,wiped free of any adhering steel wool, washed with carbon tetrachloride,air-dried and then weighed to 0.1 milligram. Three hundred cc.

of the oil to be tested is placed in a 500 cc. lipless glass (1)--Bright (2 )Stained (3 )Grey-black (4 Black, smooth 5 Black, flakeAfter the visual inspection of the silver strip is immersed in apotassium cyanide solution at room temperature until the silver surfaceassumes its original bright or silver appearance. The silver strip isthen washed successively with distilled water and acetone, air-dried andweighed. A weight loss of 20 mg. or less is considered passing.

Example I A charge of 91 grams (0.33 mole) of molybdenum pentachlorideand 100 ml. of benzene was placed in a glass reaction vessel equippedwith a reflux condenser, thermometer, a dropping funnel and a stirrer.Thereafter, 306 grams (1.0 mole) of di-(Z-ethylhexyl) phosphite in 200ml. of benzene was added dropwise with stirring at room temperature overa period of 2.5 hours. At the end of the addition of thedi-(Z-ethylhexyl) phosphite the temperature of the resulting reactionmixture had risen to 35 C. Thereafter, the resulting mixture was stirredand heated under refluxing conditions for a period of one hour. At theend of the heating period the reflux condenser was removed from thereaction vessel and a porous glass gas dispersion tube was inserted intothe reaction medium. Thereafter nitrogen was passed thru the reactionmixture, with continued heating and stirring, to remove the benzene andhydrogen chloride formed by the reaction, until no more odor of benzeneand hydrogen chloride was noted at which time the reaction temperaturewas 130 C. After cooling, a deep purple liquid reaction product wasobtained which analyzed 8.2% molybdenum, 9.67% chlorine, and 5.31%phosphorus.

The product was tested at the 0.5% concentration level in solventextracted SAE 40 grade Mid-Continent oil containing about 2.8% of adetergent of the barium neutralized phosphorus sulfide-polybutenereaction product type. The oil gave a bright EMD silver strip and MSSCTweight losses of 234.1 mg. at 48 hours and 315.2 mg. at 72 hours,whereas the same oil without the product of this example gave a MSSCTloss of 870.4 mg. at 48 hours.

In the preparation of the novel oil-soluble organomolybdenum products ofthe present invention it is advisable to use an inert solvent or diluentfor the reactants. Inert solvents which have been found suitable for useare those having boiling points within the range of from about 75 C. toabout C. such as, for example, benzene and toluene.

The hydrocarbyl substituted phosphites which are used as reactants inthe preparation of the oil-soluble organomolybdenum products of thisinvention are readily available from the reaction of phosphorustrichloride with one or more of the appropriate alcohols. This reactionis well known and in the case of alcohols generally requires a molarratio of reactants of 3:1 (alcoholaphosphorus trichloride). The alcoholsmay be pure materials or mixtures containing varying chain lengthsdepending upon their origin. Inasmuch as the alcohols used in thepreparation of the substituted phosphites may be mixtures, it will beapparent that the di-hydrocarbyl substituted phosphites will containhydrocarbyl substituents of varying chain lengths. Consequently R in thegeneral formula (RO) --POH may be the same or different. It is onlyessential that R contain at least four carbon atoms so as to impart oilsolubility to the final organo-molybdenum product of the invention.

While the above-described reaction products can be suitably employedalone in combination with a base oil, they are usually used incombination with other lubricant addition agents which impart variousdesired characteristics to the base oil. Usually, these reactionproducts are used in conjunction with detergent-type additives,particularly those which contain sulfur or phosphorus and sulfuraddition agents. This type is usually used in amounts of from about0.002% to about 10%, and preferably from about 0.01% to about 5%. Amongthe phosphorusand sulfur-containing addition agents are the neutralizedreaction products with a phosphorus sulfide and a hydrocarbon, analcohol, a ketone, an amine or an ester. Of the phosphorus sulfidereaction product additives, I prefer to employ the neutralized reactionproducts of a phosphorus sulfide, such as a phosphorus pentasulfide, anda hydrocarbon of the type described in US. 2,316,082, issued to C. M.Loane et al., April 6, 1943. As taught in this patent, the preferredhydrocarbon constituent of the reaction is a mono-olefin hydrocarbonpolymer resulting from the polymerization of low molecular weightmono-olefin hydrocarbons, such as propylene, butenes, amylenes orcopolymers thereof. Such polymers may be obtained by the polymerizationof mono-olefins of less than 6 carbon atoms in the presence of acatalyst, such as sulfuric acid, phosphoric acid, boron fluoride,aluminum chloride, or other similar halide catalysts of the Friedel-Crafts type.

The phosphorus sulfide-hydrocarbon reaction product normally shows atitratable acidity which is neutralized by treatment with a basicreagent. The phosphorus sulfidehydrocarbon reaction product, whenneutralized with a basic reagent containing a metal constituent, ischaracterized by the presence or retention of the metal constituent ofthe basic reagent.

The neutralized phosphorus sulfide-hydrocarbon reaction product can beobtained by treating the acidic reaction product with a suitable basiccompound, such as hydroxide, carbonate, oxide or sulfide of an alkalineearth metal or an alkali metal, such as for example, potassiumhydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, bariumhydroxide, barium oxide, etc. Other basic reagents can be used, such asfor example, ammonia, or an alkyl or aryl-substituted ammonia, such asamines. The neutralization of the phosphorus sulfide-hydrocarbonreaction product is carried out preferably in a non'oxidizing atmosphereby contacting the acidic reaction product either as such or dissolved ina suitable solvent, such as naphtha with a solution of the basicreagent. As an alternative method, the reaction product can be treatedwith solid alkaline compounds, such as KOH, NaOH, Na CO CaO, Ba(OH) NaS, and the like, at an elevated temperature of from about 100 F. toabout 600 F. Neutralized reaction products containing a heavy metalconstituent, such as, for example, tin, titanium, aluminum, chromium,cobalt, zinc, iron and the like, can be obtained by reacting a salt ofthe desired heavy metal with the phosphorus sulfide-hydrocarbon reactionproduct which has been treated with the phosphorus sulfide-hydrocarbonreaction product, which has been treated with a basic reagent, such asabove-described.

Other phosphorus sulfide reaction products which can be used are thereaction products of a phosphorus sulfide and a fatty acid ester of thetype described in US. 2,399,- 243; the phosphorus sulfide-degrasreaction products of US. 2,413,332; the reaction product of an alkylatedphenol with the condensation product of P S and turpentine of US.2,409,877 and U.S. 2,409,878; the reaction product of a phosphorussulfide and stearonitrile of U.S. 2,416,- 807, etc.

The above described molybdenum compounds can be used in combination withlubricant base oils, such as hydrocarbon oils, synthetic hydrocarbonoils, such as those obtained by the polymerization of hydrocarbons, suchas olefin polymers, for example, polybutenes, polypropylene and mixturesthereof, etc.; synthetic lubricating oils of the alkyleneoxide type, forexample, the Ucon oils, marketed by Carbide and Carbon Corporation, aswell as other synthetic oils, such as the polycarboxylic acid ester-typeoils, such as the esters of adipic acid, sebacic acid, maleic acid,azelaic acid, etc.

While this invention has been described in connection with the use ofthe herein-described additives and lubricant compositions, their use isnot limited thereto; but the same can be used in products other thanlubricating oils, such as for example, fuel oils, insulating oils,greases, non-drying animal and vegetable oils, waxes, asphalts, and anyfuels for internal combustion engines, particularly Where oxidation mustbe combatted.

Concentrates of a suitable oil base containing more than of anoil-soluble reaction product of molybdenum pentachloride and ahydrocarbyl substituted phosphite alone or in combination with otheradditives can be used for blending with hydrocarbon oils or other oilsin the proportions desired for the particular conditions of use to givea finished product containing at least 0.2% of the molybdenum carbonylcompound.

Percentages given herein and in the appended claims are weightpercentages unless otherwise stated.

Although the present invention has been described with reference tospecific preferred embodiments thereof, the invention is not to beconsidered as limited thereto but includes within its scope suchmodifications and variations as come within the spirit of the appendedclaims.

I claim:

1. A mineral lubricating oil containing from about 0.2 to about 0.5% ofthe reaction product obtained by reacting at a temperature of from 20 toabout 140 C. 1 mole of molybdenum pentachloride and 3 moles of aphosphite having the formula HOP(OR) wherein R is a C hydrocarbylradical of the group consisting of alkyl and cycloalkyl radicals; andfrom about 0.002 to about 10% of a sulfur-containing detergent normallycorrosive to silver.

2. A mineral lubricating oil containing from about 0.2 to about 0.5% ofthe reaction product obtained by reacting at a temperature of from 20 toabout 140 C. 1 mole of molybdenum pentachloride and 3 moles of a di-(Calkyl) phosphite; and from about 0.002 to about 10% of asulfur-containing detergent normally corrosive to silver.

3. The lubricating oil of claim 2 wherein said phosphite is dioctylphosphite.

4. A mineral lubricating oil containing from about 0.2 to about 0.5% ofthe reaction product obtained by reacting at a temperature of from 20 toabout 140 C. 1 mole of molybdenum pentachloride and 3 moles of aphosphite having the formula HOP(OR) wherein R is a C hydrocarbylradical of the group consisting of alkyl and cycloalkyl radicals, andfrom about 0.002 to about 10% of a metal-containing neutralized reactionproduct of phosphorus sulfide and an olefin polymer wherein said metalis a member of the group consisting of alkali and alkaline earth metals.

5. The lubricating oil of claim 4 wherein said metal is barium.

6. The lubricating oil of claim 5 wherein R is C alkyl; and said olefinpolymer is polybutene.

7. A mineral lubricating oil containing about 0.5% of the reactionproduct obtained by reacting at a temperaure of from 20 to about 140 C.1 mole of molybdenum pentachloride and 3 moles of di-(2ethylhexyl)phosphite, and about 2.8% of the barium-containing neutralized reactionproduct of phosphorus sulfide and polybutene.

References Cited by the Examiner UNITED STATES PATENTS 2,818,417 12/57Brown et al. 260429 2,849,399 8/58 Matuszak et a1 25232.7 2,850,452 9/58Sands et a1. 25232.7 2,866,732 12/58 HOE et al 260429 X 2,952,523 9/Podall 260-429 X 2,964,547 12/60 De Witt et al. 260-429 3,068,259 12/ 62Hartle 252-32] DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, JOSEPH R. LIBERMAN,

Examiners.

4. A MINERAL LUBRICATING OIL CONTAINING FROM ABOUT 0.2 TO ABOUT 0.5% OFTHE REACTION PRODUCT OBTAINED BY REACTING AT A TEMPERATURE OF FROM 20 TOABOUT 140*C. 1 MOLE OF MOLYBDENUM PENTACHLORIDE AND 3 MOLES OF APHOSPHITE HAVING THE FORMULA HOP(OR)2 WHEREIN R IS A C4-18 HYDROCARBYLRADICAL OF THE GROUP CONSISTING OF ALKYL AND CYCLOALKYL RADICALS, ANDFROM ABOUT 0.002 TO ABOUT 10% OF A METAL-CONTAINING NEUTRALIZED REACTIONPRODUCT OF PHOSPHORUS SULFIDE AND AN OLEFIN POLYMER WHEREIN SAID METALIS A MEMBER OF THE GROUP CONSISTING OF ALKALI AND ALKALINE EARTH METALS.